Kiln



March 28, 1933u 1 L, LADD 1,903,118

KILN

Filed Sept. 28, 1951 2 Sheets-Sheet l L. L. LADD `March 28, 1933.

KILN

2 Sheets-Sheet 2 Filed Sept. 28

Patented Mar. 28, 1933 UNITED STATES LESTER L. LADD, OF LOCKPORT,ILLINOIS KILN Applicationled September 28, 1931. Serial No. 565,502.

This invention relates to tunnel kilns used in firing ceramic ware. f

Tunnel kilns may be classied as open iring kilns or mule kilns. Intheopen type of kiln, the combustion gases are discharged directly into theware passage. In the mulile type of kiln, a refractory muiilewall'separates the Ware passage from the combustion chamber to preventthe flames and gases of incomplete combustion such as carbon monoxidefrom reaching. the ware.

The open type of kiln is very eficient but those heretofore in use havenot been adapted for firing certain kinds of ware, such as 5 glost Ware,because the flames and carbon monoxide came into direct contact with theware and discolored the glazed coatings.

The muiile type of kiln is not so eiiicient as an open kiln, but it issafer and more satisfactory for some purposes because the mufHe preventsthe flames and combustion gases from injuring the ware.

The main objects of this invention are to provideV a tunnel kiln of theopen type which approaches the safety of a mufHe kiln.; to provideimproved means for withdrawing carbon monoxide from the combustionchamber and the ware passage to provide an improved forin of baillewhich will prevent the flames from striking the ware but which willpermit communication between the combustion chamber and the warepassage; to'provide a baffle of this kind which will permit the roof ofthe tunnel to move freely when expanding and contracting undertemperature changes; and to provide a construction of this kind which isadapted for use in connection with tunnel kilns of the straight orcircular type. v

An illustrative embodiment of this invention is shown in theaccompanying drawings wherein:

Figure 1 is a top plan of a circular tunnel kiln, to'which thisinvention is applied.

Figure 2 is an enlarged transverse vertical section of the kiln at thefiring zone.

Fig. 3 is a horizontal section, taken on the line 3 3 of Fig. 2.

Fig. 4 is al fragmentary side elevation of one of the baille walls.

In the form shown, the kiln is of the circular type comprising anannular conveyer 1 movable through an open loading and unloading zone 2,and through an arcuate tunnel 3 having a preheating zone 4,'firing zone55 5 and cooling zone 6.

The conveyer may be of the type shown in my co-pending applicationSerial 366,959 filed May 29, 1929 which has become Patent 1,842,411. Itcomprises an annular platform '60 7, provided with the usual aprons 8,and supported on an annular I-beam 9, to which is attached a mono-rail10, which rides on a plurality of supporting wheels 10.1. Certain of thesupporting wheels are motor driven for driving the conveyer.

The tunnel is supported on a fabricated metal frame structure comprisingvertically disposed angle bars 11 and 12, which are connected tohorizontal bars 13 and 14. The 70 upper ends of the bars 11 are securedagainst spreading by horizontal tie rods 15, which are disposed abovethe tunnel. Supported on the frame bars 14, are concrete floor slabs 16disposed on respectively opposite sides of the 75 conveyer. Formed atthe inner edges of these floor slabs, are troughs 17, which are filledwith sand or other suitable sealing material adapted to coact with theaprons 8 to prevent the heat in the ware passage from reaching thebearings of the conveyer. Metal shields 18 form the inner walls of thetroughs 17. Y

VIn the form shown, the tunnel 3 comprises a floor 19, side wall 20, anda roof 21, which define the preheating zone 4, firing zone 5 and coolingzone 6. Inasmuch as this invention relates primarily to the tunnelconstrucvion within the firing zone, the other zones have not been shownin detail.

The tunnel varies in cross section at different zones of the kiln.Extending through the tunnel is a central ware passage 22 through whichthe ware travelsin the direction of the arrow shown in Fig. 1. Mycopending application Serial No. 565,501, filed September 28, 1931,shows a tunnel Ventilating system which is well adapted for use inconnection with a kiln to which this invention is applied.

The floor, Walls, and roof of the kiln may be made of various heatresisting materials such as brick, fire brick, tile, refractory,infusorial earth, and similar materials.

In the firing zone, the tunnel is formed to provide a pair of combustionchambers 23 located on respectively opposite sides of the ware passage22. Fuel is delivered to these combustion chambers through nozzles 24which extend into openings 25 in the side walls 20. The nozzles 24 areconnected to manifolds 26 of a fuel supply system.

Located on respectively opposite sides of the waie passage in the firingzone, is a pair of battles, each of which includes a pair of verticallydisposed walls 27 and 28, which are mounted on the tunnel flo-or 19 andwhich are spaced from each other. Formed in these walls, are openings 29to provide communication between the lower portions of the combustionchambers 23 and the ware passage 22. The openings 29 of the walls 27 arestaggered witli respect to those `of the walls 28, so as to prevent the[laines from entering the ware passage.

The inner walls 27 have outwardly proj ecting ledges 30 which rest uponthe upper ends of the walls 28. As shown in Figure 2, the upper ends ofthe baille walls are disjoined from the tunnel roof, so as to permit theroof to freely expand and contract under temperature changes. In orderto prevent communication between the upper ends of the combustionchambers 23 and the ware passage, the baliie walls 27 are imperforateabove the ledges 30, and the tunnel roof is provided with inclinedaprons or shields 31 which engage the outer faces of the walls 27. Theseaprons 31 form, in effect, movable sections of the bali'le walls 27.They permit the tunnel roof t-o expand and contract but they prevent anyof the combustion gases in the upper portions of the chambers 23 frompassing into the ware passage.

Carbon monoxide, which is the most injurious of all the gases ofincomplete compustioii, is very light and usually floats to the upperportions of the combustion chambers and ware passage. In order to skimolf this injurious gas, to prevent damage tothe ware, the tunnel roof isprovided with a plurality of outlet pipes 32 leading to a manifold 33connected to an exhaust fan 34.

In the form shown, the tunnel is provided with grooves 85 in the roofand floor of the firing zone so as to permit the insertion of animperforate baille 36 if one is desired.

In operation, the ware is loaded lon the conveyer l in the zone 2 and itis moved successively through the preheating zone, firing zone andcooling zone of the kiln.

In the combustion chambers, the flames from the nozzles 24 strikeagainst the bafile walls 27 and 28 and are thereby prevented fromdamaging the ware within the passage 22. Most of the carbon monoxidewithin the combustion chambers rises to the top where it is trapped bythe walls 27, aprons 31, and ledges 30. Some of the carbon monoxide mayescape through the openings 29 but it would then rise to the upper partof the ware passage.

'Ilie exhaust fan 34 operates continuously and the lighter gases,including the carbon monoxide, are thereby withdrawn from the combustionchambers and the ware passage. With this improved construction, the warepassage is substantially free from any gases of incomplete combustionwhich would injure the ware.

Although but one specific embodiment of this invention has been hereinshown and described, it will be understood that certain details of theconstruction shown may be altered or omitted without departing from thespirit of the invention as defined by the following claims:

I claim:

l. A kiln comprising a tunnel having a ware passage and acontiguouscombustion chamber communicating with each other attheir lower ends, asubstantially imperforate battle separating the upper portions of saidware passage and combustion chamber from each other, and means at theupper end of said combustion chamber for withdrawing" the liohtercombustion gases.

2. kiln comprising a tunnel having a ware passage and a contiguouscombustion chamber, a vertical battle arranged between said ware passageand combustion chamber,

the upper portion of said baille being substantially impervious togases, the lower portion of said battle being perfor-ate to permitcertain of the combustion gases to enter said chamber, and a pair ofvertical baffle walls arranged between said passage and chamber andspaced from each other, said bafiie walls having staggered openingsforming tortuous passages providing communication between said chamberand ware passage.

4. A kiln comprising a tunnel having side walls and a roof defining aware passage and a contiguous combustion chamber, a vertical bafflemounted on the iioor of said tunnel f and being perforated to permitcommunication between said chamber and passage, the upper end of saidbaffle being disjoined from said roof to permit said roof to freelyexrdv: ware passage, and means for withdrawing CTI pand and contract,and an imperforate skirt Y depending from said roof and slidably en-y{raging one side of said baile so as to form a movable section thereof.

LESTER L. LADD.

